Drop obsolete extra logic which treats the zone name as covered network
name in case the network list is unset. This behaviour applied to the
pre-fw3 uci firewall, but is not supported since fw3 anymore.
Ref: https://forum.openwrt.org/t/luci-zone-creation-bug/55921
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
When checking for an existing zone with the same name internally,
addZone() must use the nonblocking lookupZone() instead of the
promise returning public getZone() call.
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
